The present invention relates to an in-line electron gun assembly of a plural beam cathode-ray tube and particularly to a ruggedizing improvement in an electrode member for such a gun assembly.
The electrode members of an in-line electron gun assembly are serially arranged to accelerate and focus a plurality of electron beams along spaced, co-planar electron beam paths. The electrode members of the gun assembly are mechanically secured by means of attachment tabs to at least a pair of insulative support rods which extend along the beam paths. Each of the electrode members commonly has several spatially-related apertures formed therein to accommodate the respective electron beams generated within the electron gun assembly. It is important that these several apertures be accurately located and aligned relative to the related apertures in adjacent electrode members, and to the respective electron generating surfaces. During the fabrication of the electron gun assembly, the attachment tabs of the various electrode members are embedded into the temporarily heat-softened insulative support rods; at which time the support rods on opposed sides of the gun assembly are pressured inwardly toward the electrode members to force the attachment tabs into the support rods. The compressive pressure tends to exert a distorting force upon the several electrode members wherein a bowing or "oil canning" effect sometimes occurs. Such bowing, however slight, changes the aperture locations relative to those in the adjacent electrode members, thereby producing deleterious inter-electrode spacing relationships within the gun assembly. The inter-electrode spacing between adjacent electrode members also can be affected by external forces acting unequally on one of the members. A getter assembly, e.g., attached to the most remote member of the electron gun assembly, may cause a variation in the inter-electrode spacing between the getter carrying member and the adjacent electrode member. Such a getter assembly is shown in the prior art structure of FIGS. 1 and 2.
A structure for ruggedizing planar electrode members which are commonly used as the control and screen grid electrodes of an electron gun assembly is disclosed in U.S. Pat. Nos. 4,049,990 and in 4,049,991. Both patents were issued to F. K. Collins on Sept. 20, 1977. In the Collins' patents, intersecting rib-like embossments are formed along the sides of the support surface of planar electrodes with at least one of the ribs extending into an attachment tab. Such a structure strengthens the supporting surface or flange portion of a planar electrode. However, such a structure provides no strengthening of the sidewall of the deep-drawn substantially cup-shaped electrode members such as the focusing and accelerating electrodes of the electron gun assembly.